Generation of surface soil Moisture Map for Indian

Using AMSR_E Sensor Data Course Seminar

forMicrowave Remote Sensing

Ajay Kumar (133040061)Civil Engg, IITB, Mumbai.

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Data Source

• Daily ascending and descending pass data can be downloaded from reverb NASA website reverb.echo.nasa.gov/.

Give coordinate for you AOI

Select starting and ending dates

Satellite and sensor selection

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Sensors specification AMSR_E (advance microwave scanning radiometer)

• Developed and provided by the Japan Aerospace Exploration Agency.• AMSR-E uses an offset parabolic reflector, 1.6 m in diameter, to focus Earth-emitted microwave radiation.Accuracy Budget• The radiometer calibration accuracy budget.• Exclusive of antenna pattern correction effects.• Errors with radiometer electronics. • The total sensor bias error ranges from 0.66 K at 100 K to 0.68 K at 250 K.Application - precipitation rate, cloud water, water vapor, sea surface winds, sea surface

temperature, sea ice concentration, snow water equivalent, and soil moisture.Source: http://nsidc.org/data/docs/daac/amsre_instrument.gd.html

AMSR-E (Aqua) 2011-2011

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Soil moisture estimation based on radiative transfer theory

The satellite measured brightness temperature (TB,p) can be expressed (Njoku et al., 2003) as:

P - polarization mode,Tau- is the upwelling atmospheric emission,Tad - is the downwelling atmospheric and spacebackground emission,τat - is the atmospheric opacity along the viewing path,εp- is the combined effective surface emissivity of vegetation, bare soil and open water,ɛp=1−rp, assuming that the transmissivity is negligible andTb,p - is the effective surface brightness temperature of the combination of vegetation, baresoil and open water within a satellite pixel at the top of the vegetation.

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Source: K. S. Alok et al. 2008

Tb,p can be defined as (Gao et al., 2006):

Tbs,p - is the bare soil brightness temperature,Tbv,p - is vegetation covered soil brightness temperature, Tbw,p - is the water brightness temperature, Cv - is the fraction of vegetation coverage and Cw - is the fractional coverage of water within a satellite pixel.

Tbs,p, Tbv,p and Tbw,p can be expressed (Mo et al., 1982; Kerr and Njoku, 1990) as:

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Ts - is the effective soil temperature (the effective temperature is the weighted-average temperature over the microwave penetration depth in the medium),ɛs,p - is the emissivity of the bare soil, Tc - is the canopy (vegetation) temperature,τc - is the vegetation opacity, ωp - is the vegetation single scattering albedo, ɛw,p - is the water emissivity and Tw - is the water temperature.

Countinued..

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Steps for soil moisture map

1. We can get 3rd level processed data for soil moisture of AMSR_E sensor which is rectified

for all corrections.

2. Calculating average ascending and descending soil moisture for a month using c

program.

3. Calculating the average of asc_avg and desc_avg for same month using c program.

4. Georeferencing image in ENVI 4.8.

5. Preparing map in arcgis.

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Georeferencing in ENVI

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Build a GLT (geographic lookup table) file:1.From the Toolbox, select Geometric Correction > Build GLT . 2.The Input X Geometry Band dialog appears. Select the band that contains the x geometry coordinates. Click OK. 3.The Input Y Geometry Band dialog appears. Select the band that contains the y geometry coordinates. Click OK. 4.The Geometry Projection Information dialog appears. In the Input Projection of Geometry Bands list, select the projection type. 5.In the Output Projection for Georeferencing list, select the projection for the georeferencing.Click OK.

Save this GLT file, it can be used to georefence any no. of image of same kind.

Detailed procedure is given http://nsidc.org/data/docs/daac/ae_land3_l3_soil_moisture/geolocate.html

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